Modern communications systems (for example, a Global System for Mobile Communications (GSM), Code Division Multiple Access 2000 (CDMA2000), a Wideband Code Division Multiple Access (WCDMA) system, and a 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) system) generally operate on a carrier lower than 3 GHz. With emergence of intelligent terminals, particularly video services, current spectrum resources can hardly meet explosive growth of a capacity requirement of a user. A high frequency band with a higher available bandwidth, particularly a millimeter-wave band, is increasingly becoming a candidate frequency band of a next generation communications system. For example, a potential available bandwidth of a carrier in a range from 3 GHz to 200 GHz is approximately 250 GHz. Therefore, in a future communications system, a high-efficiency signal sending method, for example, a sending method with a low peak-to-average ratio, needs to be taken into consideration, to reduce a requirement for a transmitter.
An orthogonal frequency division multiplexing (OFDM) technology is generally used for downlink signal transmission in a current LTE system. With features such as a strong anti-multipath interference capability, simple implementation of a discrete Fourier transform, and being favorable to a multi-antenna transmission technology, the OFDM technology is extensively studied and applied. A discrete Fourier transform-spread-OFDM (DFT-S-OFDM) solution is used for uplink signal transmission. Peak-to-average ratio performance of a DFT-spread-OFDM signal is close to that of a single carrier signal. When subcarrier groups occupied by different user equipment do not overlap, orthogonal frequency division multiplexing can be implemented, so as to obtain a single carrier orthogonal frequency division multiple access solution.
Single carrier frequency division multiple access (SC-FDMA) transmission that is based on DFT-S-OFDM and defined in the current LTE means that a time domain signal envelope before a DFT transform is performed meets a single carrier characteristic or has a relatively good peak-to-average ratio characteristic (or a relatively good cubic metric (CM) characteristic), so that a relatively low peak-to-average ratio of a transmit signal can be obtained. In a frequency domain, the SC-FDMA transmission can be implemented in a centralized manner or a distributed manner. In centralized SC-FDMA transmission, one transmit signal of one UE occupies a contiguous frequency spectrum in the frequency domain (that is, frequency domain subcarriers are contiguous), and occupies a part of an entire system bandwidth. In distributed SC-FDMA transmission, one transmit signal of one UE occupies multiple non-contiguous equally-spaced subcarriers in the frequency domain. Frequency division multiplexing may be performed on two channels of one user equipment or two channels of two user equipment, thereby ensuring that there is little interference between the two channels. For transmission of multiple signals or channels of one UE, to keep peak-to-average ratio performance close to that of a single carrier signal, an uplink control channel and an uplink reference signal (for example, a demodulation reference signal (DMRS)) of each terminal device are transmitted in a time division multiplexing manner, or an uplink data channel and an uplink reference signal of each user are transmitted in a time division multiplexing manner. That is, the multiple signals or channels are sent on different time domain symbols, so as to keep low peak-to-average ratio performance that is close to that of single carrier signal transmission.
However, in the prior art, there is no technical solution in which a terminal device simultaneously sends two frequency-division and orthogonal signals on one time domain symbol and can reduce a high peak-to-average ratio caused by superposition of the two signals.